Chris Martin has ruled out collaborating with Justin Bieber because he’s scared that the teen idol will make him look old. Martin said this before his band ‘Coldplay’ set at the Wembley Stadium event, where they performed at the Capital FM Summertime Ball in front of 80,000 fans. “Rihanna was top of our list of collaborators, and we’ve done that. She was lovely – she was cool,” a leading daily has quoted the singer as saying. “We’d work with anyone who wanted to work with us. But Justin Bieber is too handsome for us. If he wants to do a video with four people who look like his grandparents then we should be in it. But we’ve got to look good. We’d just look terrible next to that guy. He’s good-looking and has an amazing complexion,” he said. Martin carried his inferiority complex on stage, when he shouted out to the crowd, “We’re Justin Bieber’s dads.” Before they played their hit ‘Charlie Brown’ under blazing sunshine Martin shouted out, “Are there any Beliebers out there?” Martin also joked before the group’s six-song set that they were only going to play Bieber covers. However, Martin does have one thing in common with the youngster – he stuffed himself with sweets before the gig because he said he needs the sugar rush for stage performances.